89 max. se stutters

[rocknrolland4x4s]

my maxima has 199k miles on it was run really good but now it stutters until 3000+ rmps i always run 97oct. has new plugs, wires, cap, rotor, k&n factor replacement locus fuel injector cleaner ran 3/4 tank of gas driving up and down the freeway. i have the car up for sale and people want to look at it to day i need help thanks for everything

[loystock]

May need a speech therapist to address the stuttering. LOL

Seriously, you may have a bad Knock Sensor and/or dirty MAF (Mass Air Flow) sensor. The Knock Sensor problem shows up at lower RPM and at 200K, it's probably shot. It will not turn on the CEL (Check Engine Light) but will store a code in the ECM. Have your car scanned at AutoZone for free. I noticed you are using a K&N filter and if it is oil-based, you definitely need to clean the MAF sensor.

Check for leaks in the air intake. You may need to service the IAC (Idle Air Control) and related valves, including the EGR. Clean the Throttle Cable and linkage to the throttle valve with WD-40.

When was the last time you have replaced the fuel filter?

Good Luck